Gastrointestinal Drugs

Question 1

Give 3 examples of PPIs?

Answer 1

Omeprazole
Lansoprazole
Pantoprazole

Question 2

What is the MoA for PPIs?

Answer 2

Bind to H+/K+ ATPase pump on gastric parietal cells

Reduces HCl production and hence reduced gastric acidity

Question 3

What are the indications for a PPI?

Answer 3

Peptic ulcers
Gastro-oesophageal reflux disease
H.Pylori infection
Prophylaxis in patients receiving long term NSAIDs
Zollinger-Ellison syndrome

Question 4

List some side effects of PPIs:

Answer 4

Nausea
Vomiting
Insomnia
Vertigo
Headaches

Question 5

What is important clinically regarding pharmaco-kinetics/dynamics for PPIs?

Answer 5

Omeprazole is an inhibitor of cytochrome P450 enzymes

Question 6

what info should be given to a patient before starting a PPI?

Answer 6

Avoid alcohol

Take 30-60mins before food

Question 7

Give 4 examples of H2 receptor antagonists

Answer 7

Ranitidine
Cimetidine
Famotidine
Nizatidine

Question 8

What is the MoA for H2 receptor antagonists?

Answer 8

Histamine binds to H2 receptors on gastric parietal cells stimulating gastric acid secretion
Drugs antagonise the effect of histamine at these H2 receptors
Reduced cAMP and hence reduced activity of H+/K+ ATPase pump

Question 9

What are the indications for a H2 receptor antagonist?

Answer 9

Peptic ulcer
Gastro-oesophageal reflux disease
Zollinger-Ellison syndrome

Question 10

List some side effects of H2 receptor antagonists:

Answer 10

Headache
Dizziness
Diarrhoea
Reduced B12 absorption
Gynaecomastia

Question 11

What is important clinically regarding pharmaco-kinetics/dynamics for H2 receptor antagonists?

Answer 11

Cimetidine is an inhibitor of cytochrome P450 enzymes.

Question 12

What info should be given to patient before starting a H2 receptor antagonist?

Answer 12

Avoid high protein diet

Take without regard to meals

Question 13

What are 2 examples of laxatives?

Answer 13

lactulose

senna

Question 14

what is the MoA for senna and lactulose?

Answer 14

Lactulose – reduces water reabsorption in intestine; it pulls water into the bowel and thus promotes distention and movement
Senna – stimulant / irritant agent

Question 15

what are the indications for a laxative?

Answer 15

pregnancy
constipation
prophylaxis in opiate analgesic use

Question 16

list some side effects of laxatives:

Answer 16

Dehydration
Salt loss
Abdominal cramps
Fatigue

Question 17

What is important clinically regarding pharmaco-kinetics/dynamics for laxatives?

Answer 17

Lactulose - consists of monosaccharides: fructose and galactose. Breakdown of this in the intestine by colonic bacteria increases osmotic pressure
Senna - recommended for short term use only. Risk of organ failure with long term use or abuse.

Question 18

What info should be given to patient before starting a laxative?

Answer 18

take liberally without regard to meals

Question 19

give examples of the different types of laxatives:

Answer 19

Bulk producing agent – adds more substance so that they can pass through intestine easily (lactulose)

Stool softeners – adds more water and fat into the stool

Stimulant or irritant – acts on intestinal mucosa and alters water and electrolyte secretion (senna)

Hydrating agents – intestines hold more water (milk of magnesia)

Question 20

what is the MoA forCyclizine?

Answer 20

Histamine H1 receptor antagonist
Acts on vomiting center in the medullary region
Mild anti-cholinergic and anbti-muscarinic effects

Question 21

what are the indications for Cyclizine?

Answer 21

Nausea and vomiting
Motion sickness
Vertigo and dizziness
Prophylaxis alongside chemotherapy and opiate analgesic use

Question 22

List some side effects of Cyclizine:

Answer 22

Headache
Sedation
Diarrhoea

Question 23

What is important clinically regarding pharmaco-kinetics/dynamics for Cyclizine?

Answer 23

It can also be a central nervous system depressant

Question 24

what info should be given to the patient before starting Cyclizine?

Answer 24

Avoid alcohol
Food may reduce irritation
Take without regard to meals

Question 25

Give 5 examples of the different types of anti-emetics

Answer 25

Anti-cholinergics (Hyoscine hydrobromide) Blocks acetylcholine neurotransmitters in the CNS and the PNS Anti-histamines (Cyclizine) H1 histamine receptor antagonist ``` Serotonin antagonists (Ondansetron) Block serotonin receptors in the CNS and the GIT ``` Phenothiazines (Prochlorperazine) Dopamine receptor antagonist (D2 receptor antagonist) ``` Motility stimulants (Metoclorpramide) Dopamine receptor antagonist (D2 receptor antagonist) ```

Question 26

What is the MoA for metoclopramide?

Answer 26

Dopamine (D2) receptor antagonist Raises activity in the chemoreceptor trigger zone – reducing input from afferent visceral nerves Also increases gastric emptying and intestinal transit Reduced oesophageal reflux

Question 27

what are the indications for metoclopramide?

Answer 27

Nausea Vomiting To increase gastric emptying

Question 28

list the side effects of metoclopramide:

Answer 28

``` Dystonia (due to dopamine antagonism) Confusion Dizziness Diarrhoea Parkinsonism with long term use ```

Question 29

What is important clinically regarding pharmaco-kinetics/dynamics for metoclopramide?

Answer 29

Can be given orally or parenterally | Dystonic reactions and movement disorders are more common at the extremes of age so caution is needed in these groups

Question 30

what info should be given to patient before starting metoclopramide?

Answer 30

avoid alcohol | Take 30 mins before meal

Question 31

what is the MoA for Prochlorperazine?

Answer 31

Penothiazine anti-psychotic drug used as an anti-emetic Dopamine (D2) receptor antagonist Causes increased dopamine turnover (in mesolimbic and chemoreceptor trigger zone)

Question 32

what are the indications for Prochlorperazine?

Answer 32

Nausea and vomiting | Used as an adjunct in some psychotic disorders

Question 33

what are the side effects of Prochlorperazine?

Answer 33

Dry mouth Tachycardia Restlessness Drowsiness

Question 34

What is important clinically regarding pharmaco-kinetics/dynamics for Prochlorperazine?

Answer 34

Anticholinergic and alpha-adrenergic receptors antagonism occurs leading to; sedation, muscle relaxation, and hypotension. The dose differs substantially when given parenterally

Question 35

what info should be given to patient before starting Prochlorperazine?

Answer 35

Avoid alcohol and caffeine | Take with food along with a full glass of water